what they are saying Nowuries, is that the plastic water bottles are oxygen permiable, IE: they actually let oxygen THROUGH the plastic. Do I buy all that jazz?? no. Do they let oxygen in? Sure, im sure they do, but not enough to matter IMHO. Its a huge debate of garbage as far as im concerned. I have 3 brews going in plastic water bottles as we speak, and I will put money on them turning out just great, and not have some "horrid VINEGAR taste" to them. I think its blown out of proportion, and over rated. Just my .02

Science really really disagrees with you. The O2 permeability of any plastic is easily researched. Science uses a lot less anecdotal evidence and a lot more... science and numbers.

I think the bucket scare thing is more about how well they close. I had an airlock run dry for a week or two and noticed vinegar production pick up quickly, I can only imagine what a poor seal on a bucket lid would do in a year or two.

Wow, this is an awesome thread. Half the posts seem to come from the realm of forum education as opposed to actual research. The question isn't whether or not you can use a food grade plastic bucket for fermenting...hell you can get a Brute garbage can and make great beer. However, when it comes to letting the beer sit in it for 2 years you have a different creature. If you go to Better Bottles website they have a few published research articles you can look at. Better Bottle does not publish their oxygen permeability because it is so low that they cannot differentiate if it is from the stopper or micro oxygenation through the plastic itself. This is possible because of how they form the plastic, which the research paper goes into specifics about. After reading it one should begin to understand that not all plastic is made equally, not all PET plastic is made equally. The PET plastic production process used to make a Better Bottle is specifically used to limit oxygen permeation. The process someone else uses to make a PET bottle may or may not be the same and yield different results. That said, unless you contact the manufacturer and find out how their bottles were produced you won't know exactly what you are dealing with. If you are going to go through all the work to make a funky beer it seems to me that it would make sense to have a good idea about the container you use so you aren't surprised with malt vinegar after 2 years of waiting.

Science really really disagrees with you. The O2 permeability of any plastic is easily researched. Science uses a lot less anecdotal evidence and a lot more... science and numbers.

I hear this sentiment a lot, but I don't hear a lot of "science and numbers" from either side on the issue. I'm baffled by how vitriolic this conversation always gets. NERDIEST. FIGHT. EVER.

I'd love to see some numbers on this issue because, as you say, I don't have anything other than anecdotal experience, and I've often wondered about the kinds of scales involved in material permeability. I don't think anybody is disputing that a sheet of HDPE allows more oxygen to permeate than a sheet of glass, but I think the question of whether or not it is a practically meaningful difference is an interesting and (as far as I've seen in my limited experience) unsolved one. So, rather than just being sarcastic, why don't you get the ball rolling for us with some data?

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Originally Posted by Bensiff

The process someone else uses to make a PET bottle may or may not be the same and yield different results.

This is key. It is broadly meaningless to talk about the oxygen permeability of plastic, because that makes it seem like high density PETG and garbage bags will demonstrate similar characteristics. Another interesting factor is whether the wall of the vessel is actually where most oxygen permeation is possible, in contrast to other things like the stopper. Anyone have any data?

I hear this sentiment a lot, but I don't hear a lot of "science and numbers" from either side on the issue. I'm baffled by how vitriolic this conversation always gets. NERDIEST. FIGHT. EVER.

I'd love to see some numbers on this issue because, as you say, I don't have anything other than anecdotal experience, and I've often wondered about the kinds of scales involved in material permeability. I don't think anybody is disputing that a sheet of HDPE allows more oxygen to permeate than a sheet of glass, but I think the question of whether or not it is a practically meaningful difference is an interesting and (as far as I've seen in my limited experience) unsolved one. So, rather than just being sarcastic, why don't you get the ball rolling for us with some data?

Oldsock's done that in the past. http://www.themadfermentationist.com...ttles-and.html has some of his info; he also brews a ton of sours, and has used glass, Better Bottles, and other fermenters, which makes the bolded somewhat more meaningful than if someone who's only done a couple brews had posted it:

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The Better Bottle website says "Virtually impermeable to oxygen"

According to Raj Apte ( http://www2.parc.com/emdl/members/apte/GingerBeer.pdf ) the material Better Bottles are made of (PETG) has an oxygen permeability about 1/6 as much as HDPE. A standard 5 gallon HDPE bucket lets in 220 cc/L per year, I assume the Better Bottle will let in about 1/6 of that or 37 cc/L per year. A regular wine barrel lets in about four times less at 8.5 cc/L per year.

I think you can reasonably assume that a barrel may let in a bit more than the math says because as a small headspace develops due to evaporation the wood above it will dry out and become more permeable.

This is all just a back of the envelope scratch calculation to give you an idea of approximately how much oxygen is getting in there. I sent an message to the folks at Better Bottle requesting any oxygen permeability stats they have, hopefully they will get back to me with some hard data.

And then:

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After a series of emails with Walter, Better Bottle Tech guy, I have some interesting things to report. First they believe that the 400 cc-mil/m2-day-Bar Raj gives for PETG is probably for a “extrusion blow material” which is different from what Better Bottles are made from, this is good news as it drags the oxygen permeability down closer to that of a regular barrel (how close I don’t know). They believe that the minimal amount of O2 coming through the plastic is dwarfed by the amount coming from the airlock/stopper which are made of much more permeable materials.

He also shot down my Brett lives on the walls because there is O2 argument. Apparently it is a biofilm, which is just something that some microbes form on wet surfaces when they are in a low nutrient environment (like fermented beer). I have seen this before on infected bottles of beer, but I have never seen it before on a carboy/fermenter.

I still think Better Bottles are a great choice for aging sour beers because it really comes down to the results.

And

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Some of my sour beers get pellicles, others don't. I actually don't notice much flavor difference between the ones that do and the ones that don't.

I'm still very happy with my results from aging in better bottles and glass carboys with airlocks. I think micro-oxygenation is one of the last issues you need to worry about.

Good god... I stand corrected, and am totally blown away at the fact that an oak wine barrel lets in that little oxygen compared to plastic.

Again, it all depends on the barrel. The bigger the barrel the less oxygen. Small 5 or 10 gallon barrels let in a lot of oxygen. However, I don't think anyone can argue with the results of products coming from 60 gallon barrels so obviously that level of permeability is a good target. If you listen to Vinnie from RR talk he recommends against using small barrels for long term aging, the numbers published in Wild Brews give a clear indication as to why.